49 lines
1.4 KiB
Markdown
49 lines
1.4 KiB
Markdown
# ADR-0008: Border strategy — session migration / portals
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- **Status:** Accepted
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- **Date:** 2026-07-30
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## Context
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A single global authoritative Minecraft simulation across many peers is unrealistic at scale (tick rate, redstone, entity AI, bandwidth). Full chunk CRDTs are also impractical for real-time play.
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## Decision
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**Coordinate-space federation** with **session migration**:
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1. Each peer owns a region with bounds/offset.
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2. Near border: plugin triggers portal or auto-migrate.
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3. Serialize player state; Protomux `flying-jib/migrate` handoff.
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4. Guest switches HyperDHT tunnel to neighbor `worldKey` and reconnects Java to localhost.
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5. Spawn at mapped coordinates.
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```mermaid
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flowchart LR
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R1["Region A Squid"] -->|"border"| Mig["Session migrate<br/>handoff + tunnel switch"]
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Mig --> R2["Region B Squid"]
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Java[Java client] -->|"reconnect localhost"| R2
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```
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**Not in v1:** streaming foreign chunks into the local Squid world or dual-sim entity forwarding.
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Later phases may add interest-based border sync without abandoning local authority.
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## Consequences
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### Positive
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- Feasible engineering path
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- Clear failure mode when neighbor offline
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- Preserves Squid as sole authority per region
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### Negative / tradeoffs
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- Reconnect hitch at borders
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- Inventory race risks (must two-phase commit — Q6)
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- Not perfectly seamless vanilla continuous terrain
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### Follow-ups
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- [ ] Phase 4 plugins + migrate state machine
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- [ ] Resolve Q6 with tests
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